1. Field of the Invention
The present invention relates to an image-taking apparatus that includes an image pickup device and generates an image signal by forming an object image on the image pickup device.
2. Description of the Related Art
Along with the development of enhanced functions in digital cameras, digital cameras incorporating shake sensors (see Japanese Unexamined Patent Publication No. 2004-72550, for example) and digital cameras including multiple preset shooting conditions respectively incorporating multiple modes for facilitating various shooting works have been placed on the market. Although a digital camera including multiple preset shooting conditions allows various shooting works, it is becoming very difficult to select a particular shooting condition and a mode incorporated in the shooting condition before shooting. In order to relieve such a complicated operation as much as possible, there have been disclosed numerous techniques applying user-friendly human machine interfaces such as a touch panel to be operated by touching a screen of a digital camera (see Japanese Unexamined Patent Publication No. 2004-48526, for example).
However, due to the increase in the number of setting modes attributable to the development of enhanced functions, it is unavoidable to complicate operations in spite of the improvement to perform setting by the touch panel operations.
Meanwhile, many image-taking apparatus include a function to adjust focus automatically, or so-called an auto focus (hereinafter referred to as AF) function in recent years. Those image-taking apparatus including the AF function include a type configured to perform focus adjustment through a photographic lens or to perform so-called through-the-lens (TTL) ranging, a type configured to perform ranging by providing multipoint ranging sensors outside a photographic light path and detecting a displacement of focused positions out of a shooting object as a phase difference (see Japanese Unexamined Patent Publication No. 11(1999)-153750). The technique according to Japanese Unexamined Patent Publication No. 11(1999)-153750 is configured to arrange multiple licensors, which are light receiving elements, depending on multiple ranging areas and to detect displacements of the focused positions of the single shooting object as the phase differences. Meanwhile, among the types configured to perform the TTL ranging, there is a type configured to apply an image pickup device as a passive-type ranging sensor and to perform shooting while automatically focusing on a region of a shooting object that shows the highest shooting object contrast (see Japanese Unexamined Patent Publication No. 2000-338387, for example). In addition, there is also a type configured to designate a ranging area by operating an operator such as an arrow key toward a certain zone in a measurable range of the image pickup device while utilizing the fact that the measurable range of the image pickup device being the passive-type ranging sensor encompasses the entire region of the shooting object, and thereby to adjust the focus such that the ranging area is set to a focused state (see Japanese Unexamined Patent Publication No. 2004-048526, for example). Moreover, among the image-taking apparatus having the AF function as described in Japanese Unexamined Patent Publication No. 11(1999)-153750, there is also a type configured to designate a ranging area by operating an operator such as an arrow key, and thereby to adjust the focus such that the ranging area is set to a focused state.
In any case, the mode configured to set up the measuring area freely will be hereinafter referred to as a wide-area AF mode in this specification.
FIG. 1 is a view showing a display screen 200 of a digital camera which is visually checked instead of a viewfinder.
Assuming that five ranging areas arranged in a cross formation are displayed on the display screen 200 shown in FIG. 1 so as to overlap a shooting object and that the mode configured to automatically focus on the region having the highest object contrast (such a mode will be hereinafter referred to an automatic AF mode) as described previously is designated, a position of a focusing lens is adjusted such that a ranging area where the highest shooting object contrast is obtained among the five ranging areas is set to a focused point.
When this automatic AF mode is designated, even in the case of attempting to focus on a bride and a groom in an upper left position shown in FIG. 1, the contrast becomes the highest in a lower right position shown in FIG. 1 between a lighted candle and a background, whereby an image tends to be shot while focusing on that position. In this case, faces of the bride and the groom may be captured within a depth of field but shot slightly out of focus.
Meanwhile, assuming that a ranging area is located fixedly in the center (such a mode will be hereinafter referred to as a one-point AF mode) and that mode is designated, an image is shot while adjusting a position of a focusing lens such that the ranging area in the center is set to a focused state. In this case, the focus may be set to an infinite position if the focusing position is set to the center.
Accordingly, when these problems are likely to occur, it is effective to reduce shooting failure by selecting the wide-area AF mode to set up the ranging area to a favorite position of a user. However, in the case of selecting one out of the five ranging areas designated in the wide-area AF mode by operating the arrow key or a touch panel as disclosed in Japanese Unexamined Patent Publication No. 2004-048526, it is necessary to take a finger off from a release button once and to concentrate on operating the arrow key or operating the touch panel when the bride, the groom and other people around them constitute the shooting object as shown in FIG. 1, for example. In this case, the user may squander a chance for a good shot if the bride and the groom move to another position or change postures in the course of the operation.